![]() The epitaxial thin films are classified as dirty-limit superconductors because their mean-free paths, which are limited by surface scattering, are smaller than their superconducting coherence lengths. We report on a study of epitaxially grown ultrathin Pb films that are only a few atoms thick and have parallel critical magnetic fields much higher than the expected limit set by the interaction of electron spins with a magnetic field, that is, the Clogston-Chandrasekhar limit. Determining the vibrations between sensor and sample in SQUID microscopy APPLIED PHYSICS LETTERS Schiessl, D., Kirtley, J.This SQUID sampler will be useful for imaging dynamics in magnetic and superconducting materials and devices. The flux noise at 4.2 K with 100 kHz repetition rate and 1 s of averaging is of order 1 mΦ0. The entire sampler device is fabricated on a 2 mm × 2 mm chip and can be scanned over macroscopic planar samples. Other design features include a micron-scale pickup loop for the detection of local magnetic flux, a field coil to apply a local magnetic field to the sample, and a modulation coil to operate the SQUID sampler in a flux-locked loop to linearize the flux response. In this work, we present the design, fabrication, and characterization of a novel scanning SQUID sampler with a 40-ps time resolution and linearized response to periodically triggered signals. The magnetic flux response of the SQUID is often linearized with a flux-locked feedback loop, which limits the response time to microseconds or longer. Scanning Superconducting QUantum Interference Device (SQUID) microscopy provides valuable information about magnetic properties of materials and devices. Micron-scale measurements of low anisotropic strain response of local T-c in Sr2RuO4 PHYSICAL REVIEW B Watson, C.We demonstrate these advances by imaging inhomogeneous diamagnetic susceptibility and vortex pinning in optimally doped yttrium barium copper oxide above 90 K. A variable-temperature sample stage that is thermally isolated from the SQUID sensor enables the measurement at sample temperatures from 2.8 K to 110 K. By implementing passive vibration isolation, we reduce relative sensor-sample vibrations to 20 nm in-plane and 15 nm out-of-plane. We mount a SQUID microscope on the 3 K plate of a Bluefors cryocooler and characterize its vibration spectrum by measuring SQUID noise in a region of sharp flux gradient. Scanning Superconducting QUantum Interference Device (SQUID) microscopy is a powerful tool for imaging local magnetic properties of materials and devices, but it requires a low-vibration cryogenic environment, traditionally achieved by thermal contact with a bath of liquid helium or the mixing chamber of a "wet" dilution refrigerator. Vice Provost for Undergraduate Education.Office of Vice President for Business Affairs and Chief Financial Officer.Office of VP for University Human Resources. ![]() Stanford Woods Institute for the Environment. ![]()
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